Carfilzomib (PR-171) is an irreversible proteasome inhibitor with IC50 of <5 nM in ANBL-6 cells, displayed preferential in vitro inhibitory potency against the ChT-L activity in the β5 subunit, but little or no effect on the PGPH and T-L activities.

Ixazomib Citrate (MLN9708) immediately hydrolyzed to MLN2238, the biologically active form, on exposure to aqueous solutions or plasma. MLN2238 inhibits the chymotrypsin-like proteolytic (β5) site of the 20S proteasome with IC50/Ki of 3.4 nM/0.93 nM in cell-free assays, less potent to β1 and little activity to β2. Phase 3.

LAT2 is degraded by proteasomes after treatment with alkylphospholipids. (A): 3-h treatment of NB4 cells before exposure to the proteasome inhibitor MG132 (10 M) prevented the reduction of LAT2 induced by 25 M ODPC. (B)(C): a similar effect was observed after exposure (30 min) of NB4 cells to the proteasome inhibitor MLN9708 (5 M) followed by treatment with 25 M ODPC (B) or 25 M perifosine (C).

MLN2238 inhibits the chymotrypsin-like proteolytic (β5) site of the 20S proteasome with IC50 and Ki of 3.4 nM and 0.93 nM in cell-free assays, respectively, also inhibits the caspase-like (β1) and trypsin-like (β2) proteolytic sites, with IC50 of 31 and 3500 nM. Phase 3.

Delanzomib (CEP-18770) is an orally active inhibitor of the chymotrypsin-like activity of proteasome with IC50 of 3.8 nM, with only marginal inhibition of the tryptic and peptidylglutamyl activities of the proteosome. Phase 1/2.

Effect of CoCl2, CEP-18770 and ONX-0914 on the expression and activity of HIF-1α. As depicted in one representative of the three performed western blots, the evaluated compounds have a profound effect on HIF-1α expression, as well on its function as it is assessed by the expression of its transcriptional target LDH-A (a).

SK-BR-3, A549, HCT-116 and BT-474 cells were incubated with or without X66 for 1 h before exposed to GM, celastrol or MG132 for 8 h. Cell lysates were analyzed by Western blot with indicated antibodies.

Epoxomicin is a selective proteasome inhibitor with anti-inflammatory activity, inhibits primarily the CH-L activity of the 20S proteasome, while T-L and PGPH catalytic activities are also inhibited at 100- and 1000-fold reduced rate.

PI-1840 is a reversible and selective chymotrypsin-like (CT-L) inhibitor with IC50 of 27 nM with little effects on the other two major proteasome proteolytic activities, trypsin-like (T-L) and postglutamyl-peptide-hydrolysis-like (PGPH-L).